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Options exist for IOL insertion in presence of compromised capsular bag
Different fixation techniques or IOLs can be used to achieve good visual acuity results.
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In our routine cataract cases, we aim to put the IOL in the capsular bag because it provides a safe and secure position that will be stable over many years. But in situations in which there is compromise to the capsular bag or the zonular apparatus, we need to look at other options for IOL placement. With the cataract safely removed and the eye in the aphakic state, we need to examine the capsular bag integrity. Is the capsulorrhexis round, well-centered and continuous? Is the posterior capsule intact? When inflating the capsular bag with viscoelastic, does it shift or deform?
In-the-bag placement
The ideal place for an IOL is typically within the capsular bag, and even in cases in which there are capsular defects, this can still be a viable option. With an irregular or radialized capsulorrhexis, there can be sufficient support and coverage of the optic edge to allow for placement of the IOL in the capsular bag. In particular, one-piece acrylic IOLs, which tend not to exert as much tension on the capsule, may pose less risk of the radialization propagating to the posterior capsule. In eyes with an intact capsulorrhexis, either a single-piece or a three-piece IOL can be placed in the capsular bag. Note that a three-piece IOL would be a better choice if there is a concern about late dislocation of the bag-IOL complex because the thin haptics can be fixated to the iris or sclera, which is not an easy option with a single-piece acrylic IOL.
If there is a focal area of zonular loss (1 or 2 clock hours), a three-piece IOL can be placed in the capsular bag with the haptics in the same direction of the absent zonules to act as a strut. If there is a larger degree of zonular loss, a capsular tension ring can be implanted as long as the anterior capsulorrhexis is intact and the posterior capsule is free from defects. This ring will exert outward pressure at the capsular bag equator and help to spread the forces evenly among the remaining zonules. For more than 6 clock hours of zonular loss, a modified capsular tension ring with an eyelet for suturing is recommended. If all zonules are present but all of them have a degree of laxity, there may not be a big advantage to using a capsular tension ring. In Figure 1, in which there was zonular laxity in all meridians, a three-piece IOL was placed in the capsular bag without a capsular tension ring. The IOL was stable at the end of the case, but if there is future instability or dislocation, the haptics of the IOL can be easily sutured to the iris.
In the ciliary sulcus
A three-piece IOL can be placed in the ciliary sulcus in the event that the posterior capsule is compromised but there is an intact anterior capsulorrhexis. Because the optic is being placed anterior to its customary position, the power should be dropped by about 1 D for most eyes (more for hyperopic eyes, less for myopic eyes). The optic can also be captured behind the capsulorrhexis with the haptics remaining in the sulcus for even more support and long-term stability. Note that other lens designs, including single-piece acrylic IOLs and plate haptic IOLs, are not suitable for placement in the ciliary sulcus.
Image: Devgan U
Iris or scleral fixation
If the capsular bag or zonules are significantly compromised, the IOL must be secured in the eye with other means. Some IOL designs, such as three-piece IOLs, can be fixated to the iris or the sclera for increased stability. For iris fixation, sutures are used to anchor the haptics to the mid-periphery of the posterior surface of the iris. Sutures can also be used to anchor the haptics to the scleral wall, although now another technique called the glued IOL technique uses intrascleral fixation of the haptics with tissue glue to close scleral flaps. This has shown to provide excellent long-term stability.
Anterior chamber IOLs
When properly sized and placed, anterior chamber IOLs provide an excellent option for eyes without capsular support. Multiple studies have shown equivalent visual results when comparing anterior chamber IOLs with iris- or scleral-fixated IOLs. In most situations, the anterior chamber IOL will be placed horizontally across the iris from the 3 to 9 o’clock position. It should be sized to be about 1 mm longer than the measured horizontal white-to-white distance. In addition, because the anterior chamber IOL optic will block the pupil, a peripheral iridectomy should be performed to allow aqueous flow. Due to their rigid, unfoldable design, anterior chamber IOLs require a larger incision of about 6 mm to 7 mm for placement. This larger incision should not be a clear corneal incision but rather a scleral tunnel, which is typically made in the superior position and then sutured at the conclusion of the case.
Once we have our IOL implanted and secured in the eye, the patient should be watched carefully in the postoperative period for signs of instability. Pseudophacodonesis, indicated by movement of the IOL upon gaze shift, is an early sign that a future intervention may be required. In cases in which we have a compromised capsular bag or zonular complex, we can still implant an IOL with excellent visual results for our patients.
- For more information:
- Uday Devgan, MD, is in private practice at Devgan Eye Surgery, Chief of Ophthalmology at Olive View UCLA Medical Center and Clinical Professor of Ophthalmology at the Jules Stein Eye Institute, UCLA School of Medicine. He can be reached at 11600 Wilshire Blvd. #200, Los Angeles, CA 90025; email: devgan@gmail.com; website: www.DevganEye.com.
Disclosure: Devgan reports no relevant financial disclosures.